Digestive System (Topic 14) Flashcards
Go over slide 2 & 3
damn already
What are gastrointestinal processes governed by? (4)
volume and composition of luminal contents and external stimuli
- The body is designed to absorb all the nutrients that are ingested, whether or not the body really needs them to function.
What does submucosal plexus do? (5)
controls secretion
What does myenteric plexus do? (5)
controls motility
Which division of the nervous system increases digestion? (5)
the parasympathetic nervous system
How does food move through the GI tract? (5)
peristalsis
- circular and longitudinal muscles working together
Where is the integrating center of short reflexes? (6)
in the enteric nervous system
(nerve plexuses)
Where is the integrating center of long reflexes? (6)
in the central nervous system
What short reflexes come from the ENS? (6)
peristalsis and secretion
What long reflexes come from the CNS? (6)
hunger, salivation in response to smell
What is chewing controlled by? (9)
by somatic nerves to skeletal muscles
What activates chewing? (9)
Rhythmic chewing motion reflexively activated by pressure of food against gums, tongue, roof of mouth.
What is the function of chewing? (9)
mechanically breaks down food to make is small enough to swallow
What is saliva produced by? (9)
salivary glands
What is saliva controlled by? (9)
sympathetic & parasympathetic neurons
- Reflex that can be conditioned by other cues (Pavlov)
What is the function of saliva? (9)
moisten and lubricate food
- small amounts of digestion
- dissolves small amounts
What stimulates swallowing? (10)
food/liquid being pushed to back of the mouth
What lets food into the stomach? (11)
lower esophageal sphincter
What are the functions of the stomach? (12)
- stores food
- some digestion
- motility for churning
- regulate entrance into the small intestine
What does the stomach secrete? (12)
HCl
What does HCl do? (12)
- kills bacteria
- denatures proteins
- converts pepsinogens to pepsins
What do pepsins do? (12)
digestive enzymes that breakdown proteins
What is chyme? (12)
solution left after digestion in stomach. Contains fragments of proteins and polysaccharides as well as droplets of fat, salts, water, etc.
Go over slide 13 & 14
ok
Why does gastrin lead to an upregulation of proton pumps? (15)
gastrin releases hydrochloric acid when food enters the stomach leading to an upregulation of the pumps
Why does ACh lead to an upregulation of proton pumps? (15)
parasympathetic nervous system releases HCl? ACh muscarinic receptors are apart of PSNS
What stimulates chief cells? (16)
enteric nervous system
Why do chief cells release inactive pepsinogen? (16)
so it doesnt degrade itself
When is pepsin activated? (16)
at high proton concentrations
What does peristalsis in the stomach do? (17)
mix the contents and close the pyloric sphincter
Why is it important that small amounts of chyme is released into the small intestine at a time? (17)
it increases the efficiency of digestion and absorption because it cannot handle it all at once
What does the pancreas secrete? (19)
- insulin and glucagon (endocrine)
- bicarbonate and digestive enzymes (exocrine)
Go over slide 20
k
What does the liver secrete? (21)
bicarbonate and bile salts
What does the liver secrete? (21)
bicarbonate and bile salts
What dies bile do? (21)
emulsify fats
- breaks it up so it can disperse in a solution
What does the hepatic portal vein do? (21)
delivers absorbed nutrients to the liver for processing before they enter the general systemic circulation.
What does the liver do? (21)
- Removes old red blood cells. Hemoglobin processing generates bilirubin.
- Synthesizes plasma proteins
What is the function of the gallbladder? (22)
stores bile
What is the function of the small intestine? (22)
digestion and absorption
What does the small intestine secrete? (22)
- digestive enzymes (amino peptides)
- salt and water (maintain fluidity)
- mucus (lubrication and protection)
What are segmentation contractions? (24)
Most frequent contractions in duodenum; least frequent in last portion of ileum.
(breaks up food)
How does peristalsis and segmentation contraction differ? (24)
no longitudinal muscle in segmentation (continue to breaks up food and mix it with digestive enzymes rather than movement down digestive system)
What is the function of the large intestine? (25)
- mostly storage and compaction of waste
- Active transport of Na+ with absorption of water.
- Contains bacteria that breakdown some undigested matter.
What do mass movement contractions do? (25)
compacts feces (3-4 times a day)
What is defecation? (25)
- Material moves to rectum. Mechanoreceptors signal urge to defecate.
- Voluntary control of external anal sphincter is learned during childhood.
What is the function of villi and microvilli? (26)
increase surface area for digestion and absorption
What are lacteals? (26)
the smallest vessels of the lymphatic system
What do sensors/neurons do? (26)
coordinate movement and secretion
What is the only kind of saccharide that can be absorbed? (27)
monosaccharides
What are disaccharidases? (27)
enzymes that breakdown dissacharides
What are disaccharidases? (27)
enzymes that breakdown dissacharides
Go over slide 18
thumbs up
How would glucose get absorbed? (28)
secondary active transport
How do monosaccharides get into the interstitial fluid? (28)
facilitated diffusion
What do endopeptidases do? (29)
breaks peptide in the middle
- 400 into two 200s
What do exopeptidases do? (29)
breaks off one amino acid at a time
- 400 into one 399 and one 1
How do protons get into the lumen? (30)
parietal cells in the stomach release protons that make their way to the small intestines lumen
Where does digestion almost exclusively take place? (31)
small intestine
What digestive enzyme breaks down fats? (31)
pancreatic lipase
what does pancreatic lipase yield? (31)
2 fatty acids and a monoglyceride
Where does lipase work? (31)
only at the surface of liquid droplets
(needed for emulsification)
What are micelles? (32)
smallest droplet from emulsion
- free fatty acids and monoglycerides
how are fatty acids and monoglycerides absorbed? (32)
diffusion
- then recombine inside the cell to from triglycerides (fat)
How are water-soluble vitamins absorbed? (34)
diffusion or mediated transport
What is celiac disease? (34)
- Loss of intestinal absorption surface due to gluten sensitivity
- Decreases absorption of nutrients
What is pernicious anemia? (34)
- Stomach portion has been removed or doesn’t secrete intrinsic factor
- Vitamin B12 not absorbed
- B12 required for erythrocyte formation
